EGU2020-6608, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Developing an integrated urban inundation flood model for extreme rainfall events with complex sewer system

Lea Dasallas and Hyunuk An
Lea Dasallas and Hyunuk An
  • Chungnam National University, Agricultural and Environmental Engineering, Daejeon, Korea, Republic of (

One of the major consequences of the changing climate is more intense rainfall episodes in climate vulnerable countries, specifically the Philippines. For over the last 10 years, extreme rainfall events had occurred in the country’s capital city, Metro Manila, which resulted to severe urban flooding occurrences.  The intense rainfall combined with the domain’s low elevation, close proximity to large water sheds and river basins, lack of proper urban planning and the un-systematized drainage system had aggravated the flood inundation. Numerous studies were conducted that had used flood models, but none of these had incorporated the effect of water drainage network, which is an integral part of simulating realistic urban flood inundation. Therefore, this research aims to develop an integrated urban inundation model based on digital surface model that assimilates the sewer system applicable for urban domains with complex pipe network. The quadtree shallow water method, a model that provides flexible grid generation that utilizes adaptive quadtree grid and cut method.  The results were analyzed and compared with the validation data obtained from previous extreme rainfall events. The integrated model was also compared to the existing flood inundation methodologies being used for the present flood early warning system. Research results show that present methodology is closer to the validated results as compared to the previous models. The developed model is also perceived to be best applicable for short term flood events. This shows the efficiency of utilizing integrated urban flood modeling in the Philippines, which can be used for extreme and conventional urban flood events in the future.

How to cite: Dasallas, L. and An, H.: Developing an integrated urban inundation flood model for extreme rainfall events with complex sewer system, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6608,, 2020

Comments on the presentation

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Presentation version 1 – uploaded on 03 May 2020
  • CC1: Comment on EGU2020-6608, Maria-Carmen Llasat, 04 May 2020

    Thank you very much for your nice presentation. As far as I understand you have incorporated the effect of water drainage network in the model of urban floods. I would like to know if you have started from the model that is running operatively now and you have improved it, or you have developed a new model. On the other hand, have you though in the possibility of using your model to simulate potential improvements in flood risk management like rainwater tanks, as is the case of Barcelona?

    • AC1: Reply to CC1, Lea Dasallas, 05 May 2020

      Good morning, Dr. Llasat, thank you for your comment! We have used an existing adaptive mesh refinement technique rainfal run-off model, but had improved the method by integrating a hypothetical sewer system. As fas as my researches goes, most of the existing flood early warning maps used in the Philippines only use elevation-based models, without the effect of sewer network. In Korea, they are beginning to introduce the sewer pipe integration in urban inundation forecasts. Which imposes less difficulty since Korea has a very detailed data of the sewage system. However, for countries like the Philippines, where water waste management is not as comprehensive, the necessity of creating hypothetical system is necessary (which will hopefully be improved as soon as more accurate data were available). We would like to test this procedure in other cases as well, given an opportunity. The comparison of  waste water system in Barcelona is an interesting insight, we would be delighted to look onto this suggestion to improve the methodology in the future. 

      • CC2: Reply to AC1, Maria-Carmen Llasat, 05 May 2020

        Thank you very much for your detailed answer, Dr. Dasallas! The responsible of the drainage network and urban pluvial floods management in Barcelona is BCASA (Barcelona Ciclo del Agua, S.A.).

        Thank you again for your presentation!

        M. Carmen Llasat

        • AC2: Reply to CC2, Lea Dasallas, 06 May 2020

          Thank you for this information, Dr. Llasat! We are very much interested to apply this method on different domains in the future. Have a nice day!